DESCRIPTION: The decay of HIV and turnover of CD4+ lymphocytes have been described recently as being very rapid suggesting that HIV replication is highly productive and that the turnover of CD4+ cells is high. This application is to extend these observations. Specific Aim 1 is to define the kinetics of decay of HIV or SIV in the compartments containing HIV by using antiviral agents. The Second Aim is to define where SIV is cleared and produced in macaques. The Third Aim is to characterize the types of lymphocytes before and after antivirals and to determine the mechanism of their regeneration. The Fourth Aim is to compare populations of HIV+ people for lymphocyte subpopulations by examining the telomeric length in sequential samples of CD4+ and CD8+ lymphocytes. The Fifth Aim is to examine CD4 and CD8 lymphocytic tissue/turnover using BrdU studies in monkeys with or without SIV infection.